Irvine-based storage products maker Western Digital said late Thursday that it has completed its acquisition of Virident Systems, the provider of flash-based storage products. The acquisition deal is worth $685M. WD had announced the acquisition last month. Virident becomes part of Western Digital's HGST subsidiary. Virident is one of two companies in the solid state storage market that Western Digital has acquired recently; the company also recently acquired solid state disk drive developer sTEC.